1. Field of the Invention
This invention relates to a trialkylsilylating agent comprising an N-(trialkylsilyl)benzanilide, and more particularly to a process for preparing an N,N-disubstituted aminotrialkylsilane by use of the silylating agent.
2. Description of the Prior Art
Heretofore, as a silylating agent for silylation of secondary amines, there have been known a number of compounds including, for example, trimethylchlorosilane, N,O-bis(trimethylsilyl)acetamide (BSA) having the following formula: ##STR2## wherein X is a hydrogen atom or a fluorine atom, and the like.
Silylation of a secondary amine by use of trimethylchlorosilane, for instance, is carried out by reacting the secondary amine and trimethylchlorosilane in the presence of amines. The reaction can be expressed as follows: ##STR3## wherein R is a hydrocarbon group such as alkyl, etc.
As is clear from the reaction equation, the silylation of a secondary amine using trichlorosilane is accompanied by formation of amine hydrochlorides as byproduct. Due to the chlorine contained in the amine hydrochloride, incorporation of the amine hydrochloride into the reaction product (silylated secondary amine) results in difficulty in using the reaction product as an electronics material, and the reaction product has an extremely limited use. The disposal of the by-produced amine hydrochloride raises another problem. Further, the silylation by use of trimethylchlorosilane has the drawback that the yield of the desired product is low.
Similarly, the silylation of a secondary amine by use of the above BSA is expressed as follows: ##STR4## wherein R and X are as defined above.
As is clearly seen from the reaction equation, only one of the two trimethylsilyl groups contained in the BSA contributes to the silylation reaction. Thus, the BSA is not high in efficiency of silylation. Also, the use of BSA for silylation results in the formation of N-trimethylsilylacetamide or N-trimethylsilyltrifluoroacetamide as by-product. These silylacetamides are sublimable and are therefore very difficult to separate by distillation. Furthermore, the BSA itself readily decomposes at a temperature of about 120.degree. C. under atmospheric pressure, and the use of the BSA as a silylating agent is greatly restricted accordingly.